Regioselectivity in the multicomponent reaction of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal under controlled microwave heating
The multicomponent reaction of 5-aminopyrazole derivatives with cyclic 1,3-dicarbonyl compounds and dimethylformamide dimethylacetal (DMFDMA) in DMF at 150 °C under controlled microwave heating afforded regioselectively 8,9-dihydropyrazolo[1,5-a]quinazolin-6(7H)-ones 6 rather than the corresponding dihydropyrazolo[5,1-b]quinazolin-8(5H)-ones 4.
α-Amino azoles in the synthesis of heterocycles: VI. Synthesis and structure of cycloalkane-annulated pyrazolo[1,5-a]pyrimidines
作者:A. A. Petrov、A. N. Kasatochkin、E. E. Emelina、Yu. V. Nelyubina、M. Yu. Antipin
DOI:10.1134/s1070428009090139
日期:2009.9
Reactions of 4-aryl-1H-pyrazol-5(3)-amines with 2-acylcycloakanones and 2-acyl-5,5-dimethylcyclohexane-1,3-diones led to the formation of regioisomeric 6,7,8,9-tetrahydropyrazolo[1,5-a]quinazoline, 5,6,7,8-tetrahydropyrazolo[5,1-b]quinazoline, and 7,8-dihydro-6H-cyclopenta[e]pyrazolo[1,5-a]pyrimidine derivatives. The product structure was determined by X-ray analysis and H-1 and C-13 NMR spectroscopy.